Advices For Studying Organic Chemistry

Two contributing Kekulé structures A representation of the resonance hybrid

1) The bonds are not alternating single and double bonds, they are a resonance

hybrid ⇒ all of the C−C bonds are the same.

4. Molecular orbital (MO) theory:

H

H H

H H

H

1) Delocalization:

2.3 POLAR COVALENT BONDS

1. Electronegativity (EN) is the ability of an element to attract electrons that it is
   sharing in a covalent bond.

1. When two atoms of different EN forms a covalent bond, the electrons are not
   shared equally between them.


2. The chlorine atom pulls the bonding electrons closer to it and becomes
   somewhat electron rich ⇒ bears a partial negative charge (δ–).


3. The hydrogen atom becomes somewhat electron deficient ⇒ bears a partial
   positive charge (δ+).
   HCl

δ+ δ−

2. Dipole:

+ −

A dipole

Dipole moment = charge (in esu) x distance (in cm)
μ = e x d (debye, 1 x 10–18 esu cm)